4.2BSD ra81 driver

[rlb at Purdue.ARPA]

From:  Bob Brown <rlb at Purdue.ARPA>

We have discovered a number of dismaying things about the 4.2BSD uda50 driver,
including a performance curve that drops like a rock under moderate load and
the occasional complete disappearence of the device.  We've fixed both these
problems and the new driver is showing two  to five times the performance
under heavy load.

Context diffs are almost as long as the driver itself.  Write or call if
you need a copy.

Bob Brown
(415)965-5407